This invention generally relates to an apparatus for encoding a first signal upon the video signal from a camera in a closed circuit television (CCTV) system so that the first signal is displayed on a video monitor as an indicator concurrently with the video from the camera. The position of the indicator on the screen of the monitor changes in response to changes in the first signal. This invention is particularly, but not exclusively, suited to provide an indicator on the screen of the video monitor in which the position of the indicator corresponds to the azimuth or compass direction of the camera.
In conventional CCTV systems, an analog signal corresponsing to the direction or azimuth in which the camera is pointing is transmitted by a transmission line separate from that transmitting the video information. For example, a DC meter calibrated in compass point directions may be used at the site of the monitor to indicate the azimuth of the camera.
Although such conventional azimuthal display systems have been generally successful, certain disadvantages have yet to be solved. Providing a separate transmission line from the video transmission line increases both the material and labor cost of the CCTV system. In typical systems in which several adjacent monitors are located for concurrent viewing, confusion may exist as to which azimuthal indicator (meter) corresponds to which monitor. Also, each DC meter used as an indicator must be individually calibrated since the resistance of each azimuthal transmission line will vary.
An object of the present invention is to provide an apparatus for encoding a data signal such as representing the azimuth of a camera in a CCTV system onto the video signal from the camera thereby eliminating the need for a separate transmission line for such data.
A further object of the present invention in providing such an encoding apparatus is to encode the data on the video signal such that a monitor concurrently displays the video image and an indicator whose position on the monitor corresponds to the data.